The invention relates to a two-stroke engine comprising a cylinder in which a combustion chamber is provided that is delimited by a reciprocating piston. The piston drives by means of a connecting rod the crankshaft rotatably supported in a crankcase. In pre-defined piston positions, the crankcase is connected to the combustion chamber by means of at least two transfer channels wherein each transfer channel opens with a transfer port into the combustion chamber. The engine comprises a device for supplying fuel and an air channel for supplying combustion air. In predetermined piston positions, the air channel is connected by a piston recess provided at the piston to the transfer ports of the two transfer channels. An exhaust for the exhaust gases generated in the combustion chamber is provided wherein the air channel opens into the cylinder bore on a side opposite the exhaust. The air channel, the piston recess, and the transfer channels define an air passage.
US 2003/0217712 A1 discloses a two-stroke engine in which combustion air is stored within the transfer channels; the transfer channels separate the exhaust gases within the combustion chamber from the fresh mixture that flows in from the crankcase. The air is supplied through an air channel that opens into the cylinder bore. In the area of the top dead center of the piston, the air channel is connected by means of a piston recess provided within the piston to two neighboring transfer channels. The air can flow through the piston recess into the transfer channels. The air channel and the mixture channel supplying the mixture to the two-stroke engine are arranged on a side of the cylinder opposite the exhaust of the combustion chamber. The air channel opens approximately horizontally into the cylinder bore. When air is flowing into the transfer channel proximal to the exhaust, the flow direction of the incoming air is deflected less than when flowing into the transfer channel that is remote from the exhaust and adjacent to the air channel. This causes a predominant portion of the scavenging air to be supplied to the exhaust-near transfer channels (transfer channels proximal to the exhaust) so that the scavenging air can pass through the exhaust-near transfer channel into the crankcase. At the same time, a complete filling with air of the transfer channels remote from (distal to) the exhaust is not achieved. This can lead to a deterioration of the exhaust gas values.